A method and apparatus for assisting in the navigation of aircraft using VOR or area navigation (RNAV) information has a digital readout operating in conjunction with a course deviation indicator (CDI) otherwise known as a D-bar. A keyboard is provided to enable the pilot to digitally enter course selection numbers for either VOR or RNAV problems. The subject method and apparatus permits the pilot to merely push a button to immediately compute the required course to center the CDI D-bar and to automatically insert the computed number into the VOR or RNAV system.

Signals comprising 30 Hz north reference and 30 Hz distance to way point vectors derived from an area navigation computer are utilized to generate a count equivalent to the true bearing (relative to north) of a way point from an aircraft. The count is used to preset a down counter operated at 400 Hz, thereby to derive in-phase and quadrature signals at 400 Hz, the phase of which are indicative of the true bearing of a way point. These signals are combined in synchronous demodulators with converted compass gyro signals at 400 Hz, and the outputs of the synchronous demodulators are summed with various positive and negative scale factors so as to generate synchro driving signals equivalent to the relative bearing of the way point with respect to the aircraft heading, thereby to drive a way point bearing indicator relatively with respect to a compass card of an RMI indicator.

An area navigation device automatically establishes waypoints along an RNAV course line intersecting with the four cardinal radials of VORTAC stations. For a given VORTAC station, the pilot selects any of the four cardinal radials and is automatically provided with the distance from the VORTAC station, along that cardinal radial, as the intersection with his selected RNAV course line. Thus, a pilot can quickly sequence through the cardinal radials and quickly ascertain the availability of waypoints along that radial. After an automatically generated cardinal waypoint is selected, it is automatically entered into memory dedicated to that waypoint for later recall and conventional use in area navigation.